Electrostriction of supported lipid films at presence of cationic surfactants, surfactant-DNA and DNA-Mg(2+) complexes

Comparative study on the interaction of DNA with three different kinds of surfactants and the formation of multilayer films

The interactions between double-stranded DNA (dsDNA) and three different kinds of surfactants, i.e., cationic, anionic, and nonionic surfactants, were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and UV-vis spectroscopy. Multilayer films composed of DNA and surfactants were prepared at gold electrode by electrostatic or hydrophobic interactions. It was found that the cationic surfactant, CTAB, can bind to DNA by electrostatic interaction, and the electron transfer resistance of CTAB-DNA complex film increases first and then decreases with CTAB concentration. The anionic surfactant, LAS, can bind to DNA but by hydrophobic interaction, and the electron transfer resistance of the complex film keeps decreasing with LAS concentration. Nonionic surfactants can also directly bind to DNA by hydrophobic interaction. All the three different kinds of surfactants can form multilayer films with DNA on the electrode surface. The chemical structure of DNA keeps unchanged during interacting with these surfactants. The binding modes of DNA with these three different kinds of surfactants were also deduced.

Improving membrane activity of oligonucleotides by cetylpyridinium chloride: an electrochemical study

The interaction of phospholipid membranes and oligonucleotides complexed with a positively charged surfactant is reported. Phospholipid membranes were assembled at the interface between an immobilized organic phase and an aqueous phase using the Langmuir-Blodgett (L-B) technique. The interaction and adsorption of the naked oligonucleotides and oligonucleotides complexed with cetylpyridinium chloride (CP) was studied electrochemically using cyclic voltammetry (CV) and ac-voltammetry. Interfacial capacitance, obtained indirectly from ac-voltammetry as a function of interfacial potential, was fitted to the theory based on the solution of the Poisson-Boltzmann equation. It was shown that both types of naked oligonucleotides (phosphoromonothioates and phosphodiesters) adsorb on the lipid monolayers poorly. The introduction of CP to the system increases the adsorption efficiency significantly. However, one phosphoromonothioate appeared to form a compact globule with CP instead of adsorbing to the lipid membrane. These results demonstrate that electrochemical methods are a powerful tool for probing the behavior of drugs in the vicinity of model cell membranes.

Preparation and phase behaviour of surface-active pharmaceuticals: self-assembly of DNA and surfactants with membranes. Differential adiabatic scanning microcalorimetric study

Some energetics issues relevant to preparation and surface characterization of zwitterionic phospholipid-DNA self-assemblies, as alternative models of the currently used problematic lipoplexes are presented. Nucleic acid compaction capacities of Mg(2+) and N-alkyl-N,N,N-trimetylammonium ions (C(n)TMA, n=12) were compared, with regard to surface interaction with unilamellar vesicles. Differential adiabatic scanning microcalorimetric measurements of synthetic phosphatidylcholine liposomes and calf thymus DNA and their ternary complexes with Mg(2+) and C(12)TMA, were employed for deduction of the thermodynamic model describing their structural transitions. Small monodisperce and highly stable complexes are established after precompaction of DNA with detergent, followed by addition of liposomes. In contrast, divalent metal cation-mediated aggregation of vesicles either leads to heterogeneous multilamellar DNA-lipid arrangements, or to DNA-induced bilayer destabilization and lipid fusion. Possible dependence of the cellular internalization and gene transfection efficiency on the structure and physicochemical properties of DNA-Mg(2+)-liposomes or DNA-cationic surfactant-liposome systems is emphasized by proposing the structure of their molecular self-organizations with further implications in gene transfer research.